Enable cpplint in media/

Bug: webrtc:5584
Change-Id: I2fd1395d35596d9002e19cc90fcda3a5d4cde9e7
Reviewed-on: https://webrtc-review.googlesource.com/16564
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20504}
diff --git a/media/engine/videoencodersoftwarefallbackwrapper_unittest.cc b/media/engine/videoencodersoftwarefallbackwrapper_unittest.cc
index c3ac434..a261ecf 100644
--- a/media/engine/videoencodersoftwarefallbackwrapper_unittest.cc
+++ b/media/engine/videoencodersoftwarefallbackwrapper_unittest.cc
@@ -330,12 +330,12 @@
 const int kMinLowDurationMs = 4000;
 const int kMinPixelsPerFrame = 1;
 const int kMinPixelsStop = 320 * 180;
-const std::string kFieldTrial = "WebRTC-VP8-Forced-Fallback-Encoder";
+const char kFieldTrial[] = "WebRTC-VP8-Forced-Fallback-Encoder";
 }  // namespace
 
 class ForcedFallbackTest : public VideoEncoderSoftwareFallbackWrapperTest {
  public:
-  ForcedFallbackTest(const std::string& field_trials)
+  explicit ForcedFallbackTest(const std::string& field_trials)
       : VideoEncoderSoftwareFallbackWrapperTest(field_trials) {}
 
   ~ForcedFallbackTest() override {}
@@ -392,7 +392,7 @@
 class ForcedFallbackTestEnabled : public ForcedFallbackTest {
  public:
   ForcedFallbackTestEnabled()
-      : ForcedFallbackTest(kFieldTrial + "/Enabled-" +
+      : ForcedFallbackTest(std::string(kFieldTrial) + "/Enabled-" +
                            std::to_string(kLowKbps) + "," +
                            std::to_string(kHighKbps) + "," +
                            std::to_string(kMinLowDurationMs) + "," +
@@ -402,7 +402,7 @@
 class ForcedFallbackTestDisabled : public ForcedFallbackTest {
  public:
   ForcedFallbackTestDisabled()
-      : ForcedFallbackTest(kFieldTrial + "/Disabled/") {}
+      : ForcedFallbackTest(std::string(kFieldTrial) + "/Disabled/") {}
 };
 
 TEST_F(ForcedFallbackTestDisabled, NoFallbackWithoutFieldTrial) {